i have a local network ranging 192.168.224.1 and default gateway 192.168.224.17 for internet
some times a system pings no ip in network unless itself, when i change the last byte of ip the problem solved but why???
for example if ip is 192.168.224.12 i change it to 192.168.224.14 and the problem solved

That depend on your network.
you change the IP manually ?
and ping from where to where?
which device you use?
Can you explain your topology?

Isp assign ips dynamically, your ip could be conflicting with the ips assigned by your isp that why when you change the last bit of your ip the system works as changing the ip will make it unique again therefore no conflicts will occur.